Contribution to the Theory of the Dielectric Properties of the Alkali Halides

1960 ◽  
Vol 119 (4) ◽  
pp. 1193-1198 ◽  
Author(s):  
E. E. Havinga
Keyword(s):  
Dielectric Properties ◽  
Alkali Halides

Interionic potentials for the alkali metal chlorides

1976 ◽  
Vol 54 (24) ◽  
pp. 3839-3849 ◽  
Author(s):  
J. Corish ◽  
Brenda M. C. Parker ◽  
P. W. M. Jacobs
Keyword(s):  
Dielectric Properties ◽  
Alkali Metal ◽  
Alkali Halides ◽  
Intrinsic Defect ◽  
Alkali Metal Chlorides ◽  
Metal Chlorides ◽  
Bulk Properties ◽  
Nearest Neighbours ◽  
Interionic Potential ◽  
Central Forces

Various models for the interionic potential in the alkali metal chlorides have been examined. The parameters in these potentials have been determined by fitting the equilibrium, elastic and dielectric properties of each substance. The potentials are compared graphically with each other, with the theoretically derived potentials of Kim and Gordon (1,2) and with a potential derived earlier by Catlow, Diller, and Norgett (3) by fitting the properties of sixteen alkali halides simultaneously. Intrinsic defect properties of the four chlorides have been calculated from these potentials. The results show that while it is possible to derive adequate two-body potentials for these salts from fitting their bulk properties, it is concluded, as found earlier by Catlow, Diller, and Norgett (3), that such potentials need to have the anion–cation interaction hardened by neglecting completely the Van der Waals interaction between nearest neighbours. Inclusion of non-central forces does not improve the potential, as judged by the criterion of the results of defect calculations.

Schottky Energy Calculations for the Alkali Halides; Details and Results of Successive Approximations

1973 ◽  
Vol 51 (18) ◽  
pp. 1923-1934 ◽  
Author(s):  
I. M. Boswarva ◽  
J. H. Simpson
Keyword(s):  
Dielectric Properties ◽  
Short Range ◽  
Negative Ions ◽  
Alkali Halides ◽  
Successive Approximations ◽  
Point Dipole ◽  
Dielectric Parameters ◽  
Continuum Region ◽  
Region I ◽  
Experimental Values

Results of theoretical determinations of the energy to form a Schottky defect, using a point-dipole model, are presented for alkali halides of the NaCl structure. The calculations were made under the following conditions: (1) Region I (in which the electrostatic and short-range interactions for each ion are treated in detail) contained 6, 18, 26, and 32 ions respectively. (2) Short-range parameters were determined from both the elastic and dielectric properties and the results compared. The "dielectric" parameters produced a better match between the dielectric properties of regions I and II (the dielectric continuum region) and showed better agreement with experimental values for the Schottky energy. (3) Derivations of detailed expressions and calculations were performed independently in two laboratories and cross-checked to eliminate errors.Region I displacements which are presented for the four cases indicate that an instability occurs in the 32-ion case for crystals in which the ions differ considerably in size. An analysis of this problem suggests that a modification of the Born repulsive energy expression is desirable when interaction between negative ions is appreciable.

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